Mixture Problem !! Weak.
 

Hi all, today i fitted a K&N panel filter to my scooby. The car now runs flat and weak, can i adjust anything to compensate for the increased airflow ? or am i going to have to refit my standard filter ? Car is a bugeye turbo prodrive.

A panel filter replacement shouldnt make much difference. Id suggest checking all the intake hoses and clips to make sure there all secure. You may have disturbed something.

unlikely that a simple change of airfilter will be the cause of such a change.

is the MAF still connected and working ?

as said a panel filter wouldnt make such a big diff' something else defo wrong

Yeah MAF is working. I am an ex car mechanic so know what i am doing etc, not worked on scooby's before mine though. The car is flatter across the whole range, a definate change i spotted when i first drove off my street. Looks like ive wasted 35 nicker. K&N panel filters normally work great on most cars through past experience.

Just to add, car runs and drives fine, just not as eager on the throttle, normally very punchy and torquey to drive.

Before condemning the K&N simply put you old filter back in and see how it runs...if it runs fine then probably worth putting the K&N back in, do an ECU reset and let it 'learn' the changes.

How do you do an ECU reset ?

ex mechanic and u need to ask??

Not worked on a Scooby before mate. No sarcastic comments needed. Thanks.

scoobys arnt the first cars to have ecu's...its a simple observation thanks....i would have thought mechanics know such things...

Cheers mate.

if it was fine before the panel filter then it may be a duff/dirty Maff now from the K&N, did you wipe all the excess oil off the filter before you fit it ?

heard the mafs dont like oil

Nothing wrong with a K and N filter for the bugeye, they are so lightly oiled.

No need to re-set as the DENSO ECU is pretty clever and will adjust fuelling / timing /IAM as it sees fit. In any case re-setting needs doing through the OBD port as disconnecting the battery just removes the "learning" aspect. Everything else is on EPROM.

Sounds as if something has been dislodged? I'd pop the old filter back in and see how the car runs :)

Shaun

No, i didnt wipe the filter, just fitted it. I will remove it tomorrow and inspect the mAF and the filter.

One point to add, my car has been set to run on 99 V power fuel, but i use 97 texaco, the car runs great but does jerk if you floor it under load, stick 99 in and it pulls like a train under load. Do you think my ECU setting is why it is more sensitive to the K&N filter change ??? Anyone ?

Was writing mine as yours was posted.

if its setup for 99..then u should use that

As above use what its mapped for. Your risking an expensive rebuild

If the car has been mapped for V power etc then that's what you should use.

However the ECU will still retain some of it's safety features and reduce the IAM if it thinks it hears det. It depends on how near the edge the mapper decided to put the engine :)

Shaun

Cheers, i dont drive the car hard, but it does jerk if you load it mid range on boost. When i bought the car it had 99 in the tank and drove like an angry beast. The nearest Shell V power station is 5 miles away, hence its not always ideal for me to drive in the opposite direction i want to go just to fuel up. Maybe i am going to have to go for a weekly trip for 99.

Do you think that is why the filter change has made a difference ?

You have repeatedly stated that the car is "running weak".

What evidence do you have for this?
I ask because weak mixture is THE fastest way to kill a Scoob engine. Trust me, it is.:(

If a car is running flat then it is running weak and not responding to the throttle. It is drawing in more air than it is fuelled for. Standard filter is going back in tomorrow then i can comment on if it has gone back to normal power.

If the MAF is disconnected would the car still run ok and smooth and perform ?

best man in world bar non !! gives advice without trying to make you look stupid! (like others!)just coz you dont know! dont make us look stupid mechanics or not. :luxhello:
cheers 99GREENWAGON!!! all the best from me !!
chris..:thumb:

Impreza's run very rich for a variety of reasons out of the box (cooling and safety)...if they start to run weak / lean then they actually start to get nearer to stoic and run more power...just before something lets go and it dies :(

The DENSO ECU can easily cope with a change of filter :)

Disconnecting the MAF on a bug doesn't have any diagnostic value as the ECU just keeps the car running

Shaun

As above: on Scoobs not true.

Can I suggest that to apply what you have learned from other cars to Scoobs might be counter-productive?

UPDATE

This morning i disconnected the MAF plug and Wd40 it, re-attached it and the car is back to normal, different exhaust note and eager on the throttle.

Glad it's back working :)

Just as an aside about filter / exhaust...., if you de-cat the Bug STi then the ECU struggles to control boost and you get boost spikes.

Shaun

and stick 99 ron in it

no probs mate.;)